Optimisation of perioperative procedural factors to reduce the risk of surgical site infection in patients undergoing surgery: a systematic review

Surgical site infections (SSI) are the leading cause of hospital readmission after surgical procedures with significant impact on post-operative morbidity and mortality. Modifiable risk factors for SSI include procedural aspects, which include the possibility of instrument contamination, the duration of the operation, the number of people present and the traffic in the room and the ventilation system of the operating theatre.The aim of this systematic review was to provide literature evidence on the relationship between features of surgical procedure sets and the frequency of SSI in patients undergoing surgical treatment, and to analyse how time frames of perioperative processes and operating theatre traffic vary in relation to the features of the procedure sets use, in order tooptimise infection control in OT. The results of the systematic review brought to light observational studies that can be divided into two categories: evidence of purely clinical significance and evidence of mainly organisational, managerial and financial significance. These two systems are largely interconnected, and reciprocally influence each other. The decision to use disposable devices and instruments has been accompanied by a lower incidence in surgical site infections and surgical revisions for remediation. A concomitant reduction in post-operative functional recovery time has also been observed. Also, the rationalisation of traditional surgical sets has also been observed in conjunction with outcomes of clinical significance.


Introduction
Surgical site infections (SSI) are the leading cause of hospital readmission after surgical procedures [1] with significant impact on post-operative morbidity and mortality [2] Modifiable risk factors for SSI include procedural aspects, which include the possibility of instrument contamination, the duration of the operation, the number of people present and the traffic in the room [3], and the ventilation system of the operating theatre [4].
These factors influence each other because preparation of instrumentation involves processes that involve a certain number of operators, each step increases the risk in contamination, and the need for different instrumentation, depending on the type of operation, can lead to altered traffic in theatre.
The need to optimise infection control in OT is accentuated by the SARS-CoV-2 pandemic and the need to prevent and respond to future epidemics. 1) What is the relationship between the features of surgical procedure sets and the frequency of surgical site infections (SSI) in patients undergoing surgical treatment? 2) How do the time frames of perioperative processes and operating theatre traffic vary in relation to the features of the procedure sets used? 3) What is the impact of streamlining and optimising surgical procedure sets and their direct and indirect costs? Figure 1 represents the flow of the literature review effected. A search through PubMed, Embase, CINAHL, Web of Science and The Cochrane Library identified 5 865 records. Five further studies were added manually after consulting the bibliographies of the articles analysed. After eliminating duplicates, the remaining records were screened by title/abstract. 98 records were assessed as eligible and analysed on full text.

Results
A total of 62 studies were excluded from the complete analysis. In conclusion, 36 studies were eligible for inclusion in the review.

Summary of evidence prior to current review
Four literature reviews relevant to the scope of the current work were identified (Table 1). In particular, Dos Santos and colleagues [6] sought to understand the main techniques and approaches in the rationalising of surgical sets, the impact on financial and operational performance, and the knowledge gaps towards which research should be directed. The review identified many studies reporting signs of improved performance both operationally, concerning set assembly, OR management and ergonomics, and efficiently in terms of washing and sterilisation processes, repair, purchasing, set-up and professional education. The authors mapped an outline for future research. Salient points to be explored are: the promotion of consensus building in multidisciplinary teams, participation in surgical set rationalisation projects and consolidation of the progress achieved; technologies for instrument tracking; cross-surgical set analysis aimed at instrument reduction; relocation of instruments excluded from sets; how to measure "non-material" and "non-tangible" benefits of set rationalisation and set safety after the process; objectives following the establishment of a surgical set rationalisation cycle.
A systematic review [7] analysed the problem of contamination of implantable instruments and devices in spinal surgery. Many studies have shown significant contamination rates. Preoperative factors, mainly related to sterilisation and device handling processes, and intra-operative factors, more dependent on personnel procedures, were noted. With respect to pre-operative factors, several studies question the overall effectiveness of sterilisation alone. At the same time, recommendations for device reprocessing are recognised as being difficult to implement in clinical settings. Regarding intra-operative processes, studies emphasise the importance of preventive practices such as changing gloves before handling implant materials, because the risk of contamination increases with exposure time [7]. 1 3

Clinical interventions to prevent surgical site infections
Three observational studies report direct evidence of an effect on the incidence of SSI (Table 2). A cohort study conducted on 233 women with ovarian and uterine neoplasms who underwent colon surgery showed a statistically significant reduction in SSIs 30 days after surgery after implementation of a preventive bundle targeting the surgical wound closure phase, including the use of a separate surgical set [10]. Two other observational studies investigated the use of disposable sets versus traditional reusable sets. The first, conducted on neuro-surgical patients undergoing lumbar fusion, observed a reduction in the incidence of SSIs from 6% in the series of 100 patients treated with reusable instruments to 2% in the series of 49 patients treated with disposable sets (p < 0.001). A significant reduction in surgical procedure duration (p < 0.05) and functional recovery time (p < 0.001) was also observed [11]. In the second, 449 orthopaedic patients underwent total knee arthroplasty using single-use instrumentation and only 0.2% underwent revision surgery for SSIs, compared to 3% (p < 0.006) of cases in a series of 169 patients operated on with conventional instrumentation [12].

Procedures for surgical tray rationalisation
Twenty-nine surgical tray rationalisations (STR) as part of quality improvement projects aimed at creating an optimised set for specific procedures.
In this context, unused items were removed from the instrument management process. The studies presented in the literature (Table 3) involved multiple branches, including: orthopaedics (n = 6), gynaecology (n = 4), ENT (n = 6), thoracic surgery, endocrine surgery, paediatric surgery (n = 2), neurosurgery, ophthalmology, vascular surgery, breast surgery (n = 2), urology, general surgery (n = 2), hand surgery, and plastic surgery. Several studies included an observation phase involving the preparation, use and reprocessing of the surgical sets between the operating theatre (OT) and the sterilisation centre (SC) (n = 13).

Processes
The rationalisation process was preceded by training and sessions to raise awareness (n = 3) aimed at increasing the degree of motivation for change and overcoming resistance that was potentially risky for the entire process.
The extent to which an instrument is used, and therefore the benefits of keeping it in the set or not, was assessed on an objective basis by analysing the data collected during the observation (n = 13), with the cut-off of use generally considered to be 20% to 25%. In other cases, the selection was made on a subjective basis by professionals (n = 3), by consensus or the collection of questionnaires on perceived use. In one case a heuristic mathematical model was developed based on a discussion with skilled surgeons on their preferences as to the composition of individual sets [10]. The model was then tested on the operating division agendas with the goal of cost-cutting.
In some cases, only surgeons were involved (n = 6). In other cases, the formation of a multidisciplinary team was promoted (n = 7).
In most of the studies, the new optimised set was presented to the clinicians for review. Devices or instruments were then added based on their opinion.
Surgical devices or instruments that were excluded were generally packaged in a dedicated set, or the original set remained available and the frequency of use of the instruments excluded was used as a marker of the safety of rationalisation.
Some studies considered a follow-up aimed at assessing the degree of satisfaction with the new rationalised set after a period of time (n = 3).

3
One study analysed the difference between the perceived use of surgical devices and instruments by the surgeons involved and their actual use determined by observation, which were respectively 37% and 55% [12].
Seven studies measured the frequency of reopening the original set in a predetermined period after optimisation. Considering that a total of eight sets were optimised, in five instances no reopening events were recorded, in the other cases the frequency of reopening was 0.9%, 6% and 10% respectively.
One study measured a reduction in the frequency of procedure cancellations following the introduction of an optimised set: incidents dropped from 3.9% to 0.2% [16]. The same study submitted a questionnaire to gather indications of staff satisfaction with the instrumentation before and after optimisation, with an increase from 1.7% to 80% [13].
Eleven studies measured the time taken to set up the operating theatre, which decreased to 2 from 5 min following the introduction of optimised sets. Other studies observed that optimisation of the set had an impact on the overall duration of the procedure, with a 5 to 6-min reduction. A reduction in the time spent cleaning the operating theatre (-25%, n = 1), and time spent by the nurse on duty outside the theatre for reasons related to retrieval of surgical instruments (-15.5%, n = 1), were also observed. One study observed downtime of 9% of the entire procedure for reasons related to locating surgical instruments [14].
Concerning costs, many studies have estimated projected cost savings in the procurement, sterilisation and processing of instruments. The average annual savings were estimated at $1 525.00 to $2 800 000.00 (n = 12), depending on the activity flow of the various hospitals involved.

Discussion
The results of the systematic review brought to light observational studies that can be divided into two categories: evidence of purely clinical significance and evidence of mainly organisational, managerial, and financial significance. These two systems are largely interconnected, and reciprocally influence each other.
The decision to use disposable devices and instruments has been accompanied by a lower incidence in surgical site infections and surgical revisions for remediation. A concomitant reduction in post-operative functional recovery time has also been observed [11].
The rationalisation of traditional surgical sets has been observed in conjunction with outcomes of organisational significance, some of which could have an indirect clinical impact. As already highlighted by previous reviews, intraoperative time and time spent by nurses outside the room, as well as the reduction of setup time [7,8] could lead to a further reduction in the time window of infection risk. Similarly, air movement in the operating room, potentially risky for contamination, could be reduced. However, studies reporting clinical outcomes as a direct consequence of organizational factors have not been found.
The effectiveness of the rationalisation of surgical sets seems to depend mainly on two conditions: the type of surgery, including the different access modes possible; and the organisational model followed. The main models observed in the interventions were Lean management and Kotter's change model. Responsibility for a training and awareness-raising process, with the active involvement of all stakeholders, appears to play a decisive role in practitioners' participation in rationalisation practices and the long-term maintenance of the results obtained.

Limits
The observational nature of all the studies identified means that the evaluations resulting from this review can be generalised taking into account the specific organisational context. This implies the need to promote future research on the topic by way of a context-specific analysis. In this context, research should consider the elements mentioned by Dos Santos and colleagues [6]: the promotion of increased consensus in multidisciplinary teams, participation in surgical set rationalisation projects and consolidation of the progress achieved; technologies for instrument tracking; a crosssectional analysis of surgical sets aimed at instrument reduction; relocation of instruments excluded from sets; how to measure the 'non-material' and 'non-tangible' benefits of rationalisation and set safety after the process; and objectives following the establishment of a surgical set rationalisation cycle. Furthermore, clinical practice could benefit from primary or secondary research design that can exemplify outputs as a result of modelling that includes an analysis of clinical or organisational improvement in relation to specific organisational, cultural and functional frameworks. It should be noted that most of the quality improvement interventions analysed did not investigate the association with direct clinical outcomes on patients such as ISS incidence, mortality and morbidity, or the occurrence of other complications, due to the nature of the project, which is also exempt from ethical approval,due to the nature of the project which was also not accompanied by ethical approval. It is considered important that organisational process indicators go hand in hand in the future with an analysis of the direct effects in the clinical field, in order to further clarify the value of the processes considered.
Most of the studies were carried out in single centres. This implies, especially as regards rationalisation of surgical sets, that the results are extremely sensitive to the organisation of individual healthcare facilities and their catchment areas.
Cost estimates presented in studies have been developed retrospectively and in some cases according to direct caseby-case analysis. These projections may be sensitive to variables not examined, including the type and overall availability of instruments in the market, and may not be generalised regardless of the country in which the study was carried out.

Competing interests All authors report no conflict of interests.
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Appendix 2. Bibliography of selected studies on full text
Agarwal, R., N, Y. Sannappavar, Appukuttan, A., Ashok, A., &Rajanbabu, A. (2019). A prospective study evaluating the impact of implementing 'bundled interventions' in reducing surgical site infections among patients undergoing